2-9
2-3 Countermeasures Against Position Deviation
Origin Search Position Deviates
• There are some reasons for position deviation after origin search completion.
• Position deviation will occur whenever the origin is searched if any coupling or joint of the machine system
has a problem.
• If the position between the origin proximity sensor and that of the encoder’s Z phase are too close to each
other, there will be a deviation of one rotation of the motor (1/2 rotation if the M Series is used).
Probable cause Item to check Countermeasure
A joint of the machine system
deviates.
• A joint of the machine system
(especially a section where parts
are connected with friction) devi-
ates.
*Such a section can be easily found
by marking it.
• Increase the joint strength.
The position of the origin proximity
sensor and that of the encoder’s Z
phase are too close to each other.
• There is a deviation of one rota-
tion of the motor (or 1/2 rotation
if the M Series is used) on
completion of origin search.
*Cause of Origin Deviation
Origin proximity sensor
Sensor deflection
Motor’s Z phase
Due to the deflection of the origin
proximity sensor, it will be un-
known whether the machine origin
will be a or b.
If the sensor is a proximity sensor,
the origin varies with the sensing
distance and ambient temperature.
• Move the position of the origin
proximity sensor for a distance
of 1/2 rotation of the motor (or
1/4 rotation if the M Series is
used).
• Loosen the coupling that con-
nects the motor shaft and the
machine system, turn the motor
shaft for 1/2 rotation of the motor
(or 1/4 rotation if the M Series is
used), and tighten the coupling
again.
The Position Control Unit Stops Abruptly.
Position Deviation with Insufficient Moving Distance Occurs.
• The Position Control Unit in positioning operation stops abruptly and then starts operating again.
• The Position Control Unit abruptly decelerates to a stop with heavy shock being imposed on the machine
system.
Probable cause Item to check Countermeasure
The incorrect deviation counter
reset or origin reset signal is input.
• The incorrect deviation counter
reset or origin reset signal is in-
put in the program.
• Correct the program.
• Noise is affecting the deviation
counter reset or origin reset
command signal line.
• Take countermeasures against
noise. Refer to Chapter 4 Coun-
termeasures Against Noise.
Connection to Position Control Unit Chapter 2
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